High-tensile steel plate giving welding heat-affected zone with excellent low-temperature toughness, and process for producing same
US9945015B2 · kind B2 · utility
Assignee
Inventors
Key dates
| Filing date | Oct 1, 2012 |
| Grant date | Apr 17, 2018 |
| Priority date | — |
| Expiry date | Aug 3, 2035 |
Classification
- Technology area (CPC C)Chemistry; Metallurgy
- CPC primaryC22C38/58
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
A high-tensile steel plate has a chemical composition containing, by mass, specific amounts of C, Mn, Si, P, S, Al, Ni, B, N, one or more elements selected from Cr, Mo, V, Cu, Ti, and Ca as needed, Ceq≤0.80, and a center-segregation zone hardness index HCS satisfying 5.5[C]4/3+15[P]+0.90[Mn]+0.12[Ni]+0.53[Mo]≤2.5. The hardness of a center-segregation zone satisfies HVmax/HVave≤1.35+0.006/C−t/750. A steel having the above-described chemical composition is subjected to hot rolling at a specific slab-heating temperature at a specific rolling reduction ratio, subsequently reheated, cooled at a cooling rate of 0.3° C./s or more until the temperature of a central portion in a plate-thickness direction reaches 350° C. or less, and tempered to a specific temperature range.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.